As the touch input method is in the spotlight as a next generation input method, attempts have been made to introduce a touch input method into a wider variety of electronic devices. Accordingly, research and development on a touch sensor capable of being applied to various environments and accurately recognizing a touch are actively conducted.
For example, in the case of an electronic device having a touch-type display, an ultra-thin flexible display which achieves ultra-light weight and low power and has improved portability has been attracting attention as a next-generation display, and development of a touch sensor applicable to such display has been required.
Flexible display means a display fabricated on a flexible substrate that can be warped, bended or rolled without loss of properties, and technological development in the form of flexible LCD, flexible OLED and electronic paper is under way.
In order to apply the touch input method to such flexible display, a touch sensor having excellent warpage and restoration force and having superior flexibility and stretchability is required.
As for the touch sensor for producing such flexible display, a wiring board including a metal wiring buried in a transparent resin substrate has been proposed. For example, a transfer-based touch sensor in which a separation layer is formed on a carrier substrate to proceed with a process, and a separation layer is used as a metal wiring coating layer when separated from the carrier substrate has been proposed (see Korean Patent No. 10-1586739).
Such a transfer-based touch sensor can be attached and applied on various substrates. However, when such substrate is a UV-impermeable substrate, it is impossible to perform adhesion with an existing UV-curable adhesive. Further, since the transfer-based touch sensor includes components that are easily corroded by acid like metal wiring, an adhesive composition having corrosion resistance is required.
Accordingly, there is a need to develop techniques for an adhesive composition which can exhibit corrosion resistance to a touch sensor while directly attaching a touch sensor such as a transfer-based touch sensor on a UV-impermeable substrate.